This invention relates to a device for collecting solar rays and transferring the heat energy contained therein to a fluid which may be circulated to any type of utilization device.
In recent years much attention has been given to alternate sources of energy as a result of increases in the cost of fossil fuels and the limited reserves of such fuels. Among the alternate sources of energy being considered, solar energy has captured the imagination of many people because of its ready availibility and absence of direct costs. Solar energy can be harnessed in a number of ways; silicon cells for instance, can be used to transfer the energy from the sun directly into electricity. Another approach, where heat energy is desired, is simply to place some type of collecting device in direct exposure to the sun's rays. Many types of heat collector devices have been proposed and built. They range from a simple metalic plate over which air is circulated to a pair of plates with a small gap therebetween in which a liquid, usually water, may be circulated to extract the heat from the plates. Many variations of this latter method have been tried to improve the efficiency of these units including the use of corrugated plates, coiled tubing, baffles, etc. There is one feature common to all these types of collectors. That is the portion of the plate directly exposed to the sun's rays is coated with a heat absorbing material such as flat black paint. This coating increases the absorbtion ability of the plate by substantially reducing the amount of the sun's rays reflected from the plate. Even with this coating however, only about 80% of the sun's rays will be absorbed by the collector while the remaining 20% is reflected and lost.
Each of the many types of collectors proposed have worked with varying amounts of efficiency and the search continues to find the most efficient and inexpensive collector device.